Filamentary Devices For Treatment Of Vascular Defects

ABSTRACT

Braid-balls suitable for aneurysm occlusion and/or parent vessel occlusion/sacrifice (e.g., in treating neurovascular defects) are disclosed. Especially for aneurysm treatment, but also for either one of the aforementioned treatments, the form of the ball is very important. In particular, the density of the device is paramount in applications where braid itself is intended to moderate or stop blood flow—allowing thrombosis within a volume formed by the ball.

CROSS REFERENCE TO RELATED APPLICATIONS

This filing is a continuation of U.S. patent application Ser. No. 12/427,620 filed Apr. 21, 2009 which claims the benefit of each of: U.S. Patent Application Ser. Nos. 61/046,594 and 61/046,670, both filed Apr. 21, 2008; U.S. Patent Application Ser. Nos. 61/083,957 and 61/083,961, both filed Jul. 28, 2008; and U.S. Patent Application Ser. No. 61/145,097, filed Jan. 15, 2009. Each of the foregoing applications is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to braid-balls suitable for aneurysm occlusion and/or parent vessel occlusion/sacrifice (e.g., in treating neurovascular defects).

BACKGROUND

Especially for aneurysm treatment, but also for either one of the aforementioned treatments, the form of the ball is very important. In particular, the density of the device is paramount in applications where braid itself is intended to moderate or stop blood flow—allowing thrombosis within a volume formed by the ball.

According to the present invention, braid-ball type implants are provided in braid of sufficient density is provided to moderate blood flow within the volume of the implant. Upon thrombosis, flow thereto is stopped. Alternatively, a blood-barrier covering can be applied to the filamentary structure to immediately stop blood flow into the vascular site, in which the implant volume is set.

In either case, to form thrombosis within the volume of the ball, the filaments of the braid matrix permit filling of the implant with blood when emplaced at a vascular treatment site. This blood then thromboses due to the flow-disruption effect(s).

Unlike Nitinol tube-cut cages that may be suitable for (or assist) in coil retention, the ball devices are adapted to work alone—or in combination with each other to effect a complete treatment. As such, high density braid/mesh is typically required. Namely, braid having at least about 48 ends, typically set at about 90 degrees or greater, in diameters from about 4 to about 8 mm may be employed. At larger diameters (e.g., about 6 to 12 or more), more wire ends (e.g., 64, 72 and upwards) may be employed in forming the balls.

Suitable braid for constructing the balls may be obtained from Secant Medical, Inc. Wire diameters may be in the range of about 0.001 to about 0.003 inches, depending on desired delivery profile (which is typically less than about 0.050 inches). The braid forming the balls may incorporate only one size wire, or may be formed with multiple sizes.

The wire is preferably superelastic NiTi alloy. The metal may be a binary alloy or a ternary alloy to provide additional radiopacity. Alternatively, radiopaque platinum fibers may be included in the braid, or the wire may comprise platinum or gold cord Nitinol DFT. Otherwise, wraps or bands (preferably Pt) used to secure the braid wire may serve as the sole radiopaque feature(s).

In any case, the construction approaches described herein enable producing these useful devices. Whether comprising braid alone, or incorporating some further blood-barrier covering (such as a thin urethane film as may be applied by Hantel, Inc. or others) the use of braid presents numerous challenges in managing the termination of multiple wires and in forming the desired structures.

Also included in the invention are detachable implant pushers that utilize a resistance wire heater to thermally sever a suture associated with the implant to effect release. As distinguished from known approaches where an implant is retained by a loop connected back to a delivery system pusher that is withdrawn with the devilry system, the present invention contemplates a leave-behind tether.

Further details, variations, modification and optional features of the invention may be appreciated by review of any of the incorporated patent applications. However, the priority date and subject matter included in the appended claims rely solely on the subject matter filed in U.S. Provisional Patent Application Nos. 61/046,670 and 61/046,594, the earliest patent applications (each filed Apr. 21, 2008) one which U.S. patent application Ser. No. 12/427,620 relies. Selected figures from the '670 and '594 application and all of text from the '594 application—all—incorporated by reference in the parent application hereto is reproduced herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph taken from U.S. Provisional Patent Appl. No. 61/046,670 (incorporated herein by reference) demonstrating actual reduction to practice of a single-layer braid ball device made according to the present invention;

FIGS. 2A and 2B are side-sectional views of the braid ball in isolation and in use, respectively;

FIG. 3 illustrates a suture-melt resistance heater pusher for implant delivery; and

FIGS. 4A-4F illustrate a production path of one implant embodiment encompassed by the current invention.

DETAILED DESCRIPTION OF THE INVENTION Implants

Referring to the figures, a filamentary implant 2 is formed out of braid to treat vascular sites. Interwoven filaments 4 form a braid matrix 6 that define a self-expandable occlusion device.

As single layer of the braid is provided in which ends of the braid are secured and managed to provide an atraumatic interface. Specifically, ties 10 (as illustrated in FIG. 1) or bands 12 (as illustrated in FIGS. 2A and 2B) secure filament the ends 14 of the braid from which the implant is constructed.

In the implant variation pictured, the expanded configuration defines an ovoid or roughly spherical shell 18 that is permeable to blood. The braid defining the proximal and distal ends of the implant turns or curves inward to a point where it is secured within the periphery of the shell.

The inversion of the braid provides recessed securement of the braid resulting in atraumatic ends of the implant. The braid filaments optionally extend beyond the securing/securement features in order to define wire filament “tufts” 20 that will further promote thrombosis of blood that enters the ball upon deployment within a patient's vasculature. However configured in regard to braid filament end securement and termination, inset ends of the braid (proximal and distal insets 22/24, respectively) are demonstrated when the implant is in an expanded state to fill an aneurysm 26 off of a vessel 28.

Delivery Systems

FIG. 3 illustrates a detachable catheter/pusher 30, optionally, for use in the present invention. Generally, it includes a resistance wire bridge 32 across insulated conductors 34 (a typical construction). What is unique is that the conductor wires are twinned/twisted along a length of the delivery pusher shaft 38 as shown. This configuration alleviates bending bias/preference. Upon application of voltage, the tip thermally severs the polymer filament (e.g., suture 40) in contact therewith. At least the suture portion is received within the implant 2 (e.g., passing through a braid-securing band 12). The suture is retained in/with the implant upon actuation to release the implant by cutting through the suture with heat. A ball stop 42 that is tied to the suture retains the filament in/with the implant is also illustrated. Finally, pusher 30 is shown received within a typical microcatheter 44 for vascular access, after passage therethough. Note also, other advantageous delivery system are referenced and described in the incorporated patent application.

Methods of Manufacture

Included in the intention is a method of manufacture including tying-off or otherwise securing a second end of a braid within an interior volume of a ball where other approaches would be impracticable. The technique may be employed in creating the balls (be they spherical or ovaloid in cross-section, etc.) out of one continuous section of braid. In so doing, joints and other delivery profile-increasing features are avoided—as well as potential areas for failure. Accordingly, the subject implants are extremely robust and fully recoverable to their aneurysmal shape as is required when they are delivered through a catheter in low profile. Robust shape recovery is required in treatments targeting distal vasculature, especially the tortuous neurovasculature encountered in human brains.

A detailed example of one process path for implant formation is illustrated in FIGS. 4A-4F. As shown in FIG. 4F an final implant 2 may begin as a section 50 of braided material. The tubular braid stock is secured. As shown, it is tied-off with a wire wrap 10. Such action develops an inset region 24 for the implant body. An opposite end of the braid is then captured in a transfer tube 52. The tube is passed through the volume of the implant and secured with a second tie 10 at the other side.

Additional refinement to the shape over that shown in FIG. 4E may be imparted within a shape-setting form 54. Mandrels 56 including stops 58 received through the securement features may be employed to force apposition of the ball to the shape of the form when pulled apart as indicated by arrows. After shape-setting in the form (as appropriate to the selected material—e.g., as in heat setting superelastic Nitinol) the mandrels are removed and the implant shaping is complete as shown in FIG. 4F. However, these additional forming steps are not necessary given that (in point of fact) the implant in FIG. 1 was produced without employing the same.

Methods of Use

Any one of the subject implants is delivered to a target site employing known percutaneous catheter access techniques. The implant may be secured to a pusher (e.g., pusher 30) used to advance it through the access catheter (e.g., microcatheter 44). Upon emplacement at the treatment site (e.g., cerebral aneurysm 26 as illustrated in FIG. 2A), the implant can be detached. With the exemplary system shown in FIG. 3, the suture 40 passing through the proximal end of the implant 2 is severed by melting it using a resistance heater. This retention/release fiber remains in and with the implant. 

1-5. (canceled)
 6. A device for treatment of a patient's vasculature, comprising: a self-expanding resilient permeable shell having a proximal end, a distal end, a longitudinal axis and further comprising: a plurality of elongate resilient filaments with a woven structure secured relative to each other at proximal ends and distal ends thereof, a radially constrained elongated state configured for delivery within a microcatheter with the thin woven filaments extending longitudinally from the proximal end to the distal end radially adjacent each other along a length of the filaments, and an expanded relaxed state with a globular and longitudinally shortened configuration relative to the radially constrained state with the woven filaments forming the self-expanding resilient permeable shell in a smooth path radially expanded from the longitudinal axis between the proximal end and distal end including a plurality of openings in the shell formed between the woven filaments, the largest of said openings being configured to allow blood flow through the openings at a velocity below a thrombotic threshold velocity.
 7. The device of claim 6 wherein at least the distal end includes a bend in a recessed configuration such that the secured distal ends of the filaments are disposed axially within a nominal contour of the permeable shell structure in the expanded state.
 8. The device of claim 7 wherein the proximal end of the shell further comprises a bend in a recessed configuration such that the secured proximal ends of the filaments are withdrawn axially within the nominal permeable shell.
 9. The device of claim 6 wherein the filaments of the permeable shell are secured relative to each other in wraps or bands.
 10. The device of claim 6 further comprising a distal hub secured to the distal ends of the filaments of the permeable shell.
 11. The device of claim 6 further comprising a proximal hub secured to the proximal ends of the filaments of the permeable shell.
 12. The device of claim 6 further comprises a band forming a cavity for a detachment tether.
 13. The device of claim 12 further comprising a detachment tether secured through the cavity of the proximal hub.
 14. The device of claim 6 wherein the filaments of the permeable shell have a transverse dimension of about 0.001 inch to about 0.003 inch.
 15. The device of claim 6 wherein the permeable shell comprises at least about 72 filaments.
 16. The device of claim 6 wherein the filaments of the permeable shell comprise a superelastic material.
 17. The device of claim 16 wherein the superelastic material comprises a shape memory metal.
 18. The device of claim 6 wherein the filaments of the permeable shell comprise a shape memory material that is heat set in a configuration of the relaxed expanded state.
 19. The device of claim 18 wherein the shape memory metal comprises a NiTi alloy.
 20. The device of claim 6 wherein the largest openings formed between adjacent filaments of a defect spanning portion of the permeable shell are about 0.017 inches to about 0.032 inches.
 21. A method of treating a vascular defect of a patient, comprising: a) providing a device for treatment of a patient's vasculature comprising a self-expanding resilient permeable shell of woven filaments, the permeable shell having a proximal end, a distal end, a longitudinal axis, a radially constrained elongated state configured for delivery within a microcatheter with the woven filaments extending longitudinally from the proximal end to the distal end radially adjacent each other, and an expanded relaxed state with a globular and axially shortened configuration relative to the constrained state with the woven filaments forming the self-expanding resilient permeable shell in a smooth path radially expanded from the longitudinal axis between the proximal end and distal end and a plurality of openings in the shell formed between the woven filaments; b) advancing a delivery system within a patient's body such that a distal end of the delivery system is disposed at a position adjacent or within a vascular defect to be treated; c) axially advancing the device for treatment of a patient's vasculature within the delivery system while in a radially constrained state with an elongate delivery apparatus which has a distal end releasably secured to a proximal end of the device for treatment of the patient's vasculature; d) axially advancing the device until the device emerges distally from a distal end of the delivery system and deploying the device such that the woven filaments of the device radially expand from their radially constrained state and expand into a globular configuration of the permeable shell which covers and acutely occludes at least a portion of an opening or neck of the vascular defect due to the pore size of the permeable shell which slows a flow of blood therethrough to a velocity below a thrombotic threshold velocity.
 22. The method of claim 21 further comprising releasing the device from the distal end of the elongate delivery apparatus.
 23. The method of claim 21 wherein the device for treatment of the patient's vasculature is positioned within the vascular defect by manipulation of a proximal end of the elongate delivery apparatus prior to release of the device.
 24. The method of claim 23 further comprising withdrawing the device partially or wholly back within the delivery system by axial retraction of the elongate delivery apparatus prior to release of the device.
 25. The method of claim 21 further comprising imparting elongation of the permeable shell in response to radial constraint due to constriction of the vascular defect.
 26. The method of claim 21 further comprising selecting a device for treatment of a patient's vasculature having a permeable shell in an expanded state with a transverse outer dimension which is oversize relative to a transverse dimension of the patient's vascular defect.
 27. A method of occluding a vascular defect of a patient's vasculature comprising providing an expandable, porous vascular occlusion device formed from a woven shell of a plurality of filamentary members that are connected to each other on at least the proximal ends of the members forming a substantially closed globular structure with a shape that approximates a size and shape of the vascular defect; collapsing the device for delivery into the vascular system of the patient; inserting the collapsed device through an incision in the patient's body; releasing and expanding the device at the vascular defect such that an outer surface contour of the device substantially fills the vascular defect; substantially occluding the vascular defect acutely with the device that is substantially covered with clotted blood.
 28. The method of claim 27 wherein the velocity of blood in the vascular defect is slowed to below a thrombotic threshold velocity after deployment of the device and thrombus forms within an interior volume of the shell of the device.
 29. The method of claim 27 further comprising selecting a device with a volume that will fill at least a portion of a volume of the vascular defect.
 30. The method of claim 29 wherein the selected device has approximately the same volume as the measured volume of the vascular defect.
 31. A delivery system for deployment of a device for treatment of a patient's vasculature, comprising: a microcatheter having an inner lumen extending a length thereof; a device for treatment of a patient's vasculature disposed within the inner lumen of the microcatheter and comprising a self-expanding resilient permeable shell of thin filaments, the permeable shell having a proximal end, a distal end, a longitudinal axis, a radially constrained elongated state configured for delivery within a microcatheter with the thin woven filaments extending longitudinally from the proximal end to the distal radially adjacent each other, and an expanded relaxed state with a globular and axially shortened configuration relative to the constrained state with the woven filaments forming the self-expanding resilient permeable shell in a smooth path radially expanded from the longitudinal axis between the proximal end and distal end and a plurality of openings in the shell formed between the woven filaments, the permeable shell further having a portion when in the expanded relaxed state that is configured to span an opening of a patient's vascular defect; and an elongate delivery apparatus having a proximal end and a distal end releasably secured to a proximal hub of the device.
 32. A method of manufacturing a device for treatment of a patient's vasculature, comprising: braiding a plurality of elongate resilient filaments over a cylindrically shaped mandrel forming a braided tubular member; heat setting the elongate filaments of the braided tubular member in an expanded relaxed state with a globular and axially shortened configuration relative to a constrained state with the woven filaments forming the self-expanding resilient permeable shell in a smooth path radially expanded from a longitudinal axis of the device between a proximal end and a distal end of the device with the shell having a bend at the distal end in an everted configuration such that a hub at the distal end is withdrawn axially within the permeable shell structure and a plurality of openings in the shell are formed between the woven filaments; securing the proximal ends of the filaments together; and securing the distal ends of the filaments together.
 33. The method of claim 32 wherein the proximal end of the device further comprises a band forming a cavity for a detachment tether.
 34. The method of claim 33 further comprising securing a detachment tether through the cavity.
 35. The method of claim 32 further comprising securing a proximal hub to the proximal ends of the filaments, securing a distal hub to the distal ends of the filaments, wherein the hubs comprise radio-opaque bands. 